bryjnar comments on Constructive mathemathics and its dual - Less Wrong

13 Post author: MrMind 28 February 2013 05:21PM

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Comment author: whpearson 28 February 2013 09:16:49PM 0 points [-]

I tend to like constructivist maths because it makes sense from a computational point of view. A boolean function may return True or False or it may not return at all (a member of the bottom set in Type theory terms) if it gets stuck in an infinite loop.

So I'm going to look at things from a computational point of view, to see if anything shakes loose. What might ~(A and ~A) represent computationally. The one thing I can think of is if A isn't a pure function, it is an unknown monad of some variety (there is some hidden state). A race condition or memory corruption that means when A is evaluated at different points in time it comes to a different value.

Going by the MWI hint, it also seems to be able to represent questions that aren't meaningful to ask. Did a particle travel through that path or did it not travel that path? Well it travelled through all possible paths, which is neither a yes or a no. You may want a logic that can represent such meaningless questions, because you can't apriori know that a question is meaningless.

Comment author: bryjnar 01 March 2013 02:08:27AM 1 point [-]

Constructivist logic works great if you interpret it as saying which statements can be proven, or computed, but I would say it doesn't hold up when interpreted as showing which statements are true (given your axioms). It's therefore not really appropriate for mathematics, unless you want to look at mathematics in the light of its computational or proof-theoretic properties.